Carbonetos de WC com fase ligante Co-Ni, comportamento da dureza e resistência à ruptura transversal em função da adição de SiC-α e seus efeitos na temperatura de sinterização

Daniel Rodrigues; Francisco Yastami Nakamoto; Givanildo Alves dos Santos; Fabio Miranda; Gilmar Ferreira Batalha; Laerte Fernandes

doi:10.4322/2176-1523.20222423

Artigo Original

Carbonetos de WC com fase ligante Co-Ni, comportamento da dureza e resistência à ruptura transversal em função da adição de SiC-α e seus efeitos na temperatura de sinterização

WC cemented carbides with based Co-Ni binder phase – hardness and transverse rupture strength behaviour as a function of SiC-α additions and their effects on the sintering temperature

Daniel Rodrigues, Francisco Yastami Nakamoto, Givanildo Alves dos Santos, Fabio Miranda, Gilmar Ferreira Batalha, Laerte Fernandes

http://dx.doi.org/10.4322/2176-1523.20222423 Tecnol. Metal. Mater. Min., vol.19, e2423, 2022

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Resumo

A vantagem de substituir o WC (15,67 g/cm3 ) pelo SiC-α (3,21 g/cm3 ) é o custo da matéria-prima e a baixa densidade do carboneto. A substituição do Co (8,90 g/cm3 ) pelo Ni (8,91 g/cm3 ), é devido à escassez da matéria-prima, restrições ao uso devido a exposição ocupacional e o preço comercial. Em relação aos experimentos realizados neste estudo, foram preparadas 3 misturas, sendo a primeira, a partir de WC-11(Co, Ni) e as demais reforçadas com adição de teores 0,6% e 1,2% de SiC-α, em peso, que foram produzidas pela técnica de metalurgia do pó convencional. Os compactados a verde foram sinterizados em fornos Sinter HIP, sinterização a vácuo em 1.380 e 1.420 ºC durante 60 minutos de estabilização e submetidos a uma pressão de 20 bar com nitrogênio. Os resultados apresentaram que com o excesso de carbono livre presente matéria-prima e mais o aumento da temperatura de sinterização influenciaram fortemente no crescimento do grão de WC e no surgimento de porosidades que consequentemente afetaram as propriedades mecânicas das ligas de metal duro.

Palavras-chave

Metalurgia do pó; Metal duro; SiC-α; Sinterização; Microestrutura e propriedades.

Abstract

The advantage of replacing the WC (15.67 g/cm3 ) with SiC-α (3.21 g/cm3 ) is the cost of the raw material and the low density. The substitution of Co (8.90 g/cm3 ) for Ni (8.91 g/cm3 ), it is due to shortages of raw material, restrictions on use due to occupational exposure and the commercial price. In relation to the experiments carried out in this work, 3 mixtures were prepared, the first being from WC-11 (Co, Ni) and the others reinforced with the addition of 0.6% and 1.2% of SiC-α, by weight, which were produced by the conventional powder metallurgy technique. The green compacted ones were sintered in SinterHIP ovens, vacuum sintered at 1,380 and 1,420 ºC for 60 minutes of stabilization and subjected to a pressure of 20 bar with nitrogen. The results showed that, with the excess of free carbon present in the raw material and the increase in the sintering temperature, strongly influence the growth of the WC grain, in the appearance of porosities that consequently affected the mechanical properties of hardmetal.

Keywords

Powder metallurgy; Hardmetals; SiC-α; Sintering; Microstructure and properties.

Referências

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Submetido em:
31/08/2020

Aceito em:
01/04/2021